@ohos.power (Power Management)

The power module provides APIs for rebooting and shutting down the system, as well as querying the screen status.

NOTE

The initial APIs of this module are supported since API version 7. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

import power from '@ohos.power';

power.shutdown

shutdown(reason: string): void

Shuts down the system.

System API: This is a system API.

Required permission: ohos.permission.REBOOT

System capability: SystemCapability.PowerManager.PowerManager.Core

Parameters

Name Type Mandatory Description
reason string Yes Reason for system shutdown.

Error codes

For details about the error codes, see Power Manager Error Codes.

ID Error Message
4900101 Operation failed. Cannot connect to service.

Example

try {
    power.shutdown('shutdown_test');
} catch(err) {
    console.error('shutdown failed, err: ' + err);
}

power.reboot9+

reboot(reason: string): void

Reboots the system.

System API: This is a system API.

Required permission: ohos.permission.REBOOT

System capability: SystemCapability.PowerManager.PowerManager.Core

Parameters

Name Type Mandatory Description
reason string Yes Reason for system reboot.

Error codes

For details about the error codes, see Power Manager Error Codes.

ID Error Message
4900101 Operation failed. Cannot connect to service.

Example

try {
    power.reboot('reboot_test');
} catch(err) {
    console.error('reboot failed, err: ' + err);
}

power.isActive9+

isActive(): boolean

Checks whether the current device is active.

System capability: SystemCapability.PowerManager.PowerManager.Core

Error codes

For details about the error codes, see Power Manager Error Codes.

ID Error Message
4900101 Operation failed. Cannot connect to service.

Example

try {
    var isActive = power.isActive();
    console.info('power is active: ' + isActive);
} catch(err) {
    console.error('check active status failed, err: ' + err);
}

power.wakeup9+

wakeup(detail: string): void

Wakes up a device.

System API: This is a system API.

System capability: SystemCapability.PowerManager.PowerManager.Core

Parameters

Name Type Mandatory Description
detail string Yes Reason for wakeup.

Error codes

For details about the error codes, see Power Manager Error Codes.

ID Error Message
4900101 Operation failed. Cannot connect to service.

Example

try {
    power.wakeup('wakeup_test');
} catch(err) {
    console.error('wakeup failed, err: ' + err);
}

power.suspend9+

suspend(): void

Hibernates a device.

System API: This is a system API.

System capability: SystemCapability.PowerManager.PowerManager.Core

Error codes

For details about the error codes, see Power Manager Error Codes.

ID Error Message
4900101 Operation failed. Cannot connect to service.

Example

try {
    power.suspend();
} catch(err) {
    console.error('suspend failed, err: ' + err);
}

power.getPowerMode9+

getPowerMode(): DevicePowerMode

Obtains the power mode of this device.

System capability: SystemCapability.PowerManager.PowerManager.Core

Return value

Type Description
DevicePowerMode Power mode.

Error codes

For details about the error codes, see Power Manager Error Codes.

ID Error Message
4900101 Operation failed. Cannot connect to service.

Example

try {
    var mode = power.getPowerMode();
    console.info('power mode: ' + mode);
} catch(err) {
    console.error('get power mode failed, err: ' + err);
}

power.setPowerMode9+

setPowerMode(mode: DevicePowerMode, callback: AsyncCallback<void>): void

Sets the power mode of this device. This API uses an asynchronous callback to return the result.

System API: This is a system API.

Required permission: ohos.permission.POWER_OPTIMIZATION

System capability: SystemCapability.PowerManager.PowerManager.Core

Parameters

Name Type Mandatory Description
mode DevicePowerMode Yes Power mode.
callback AsyncCallback<void> Yes Callback used to return the result. If the power mode is successfully set, err is undefined; otherwise, err is an error object.

Error codes

For details about the error codes, see Power Manager Error Codes.

ID Error Message
4900101 Operation failed. Cannot connect to service.

Example

power.setPowerMode(power.DevicePowerMode.MODE_PERFORMANCE, err => {
    if (typeof err === 'undefined') {
        console.info('set power mode to MODE_PERFORMANCE');
    } else {
        console.error('set power mode failed, err: ' + err);
    }
});

power.setPowerMode9+

setPowerMode(mode: DevicePowerMode): Promise<void>

Sets the power mode of this device. This API uses a promise to return the result.

System API: This is a system API.

Required permission: ohos.permission.POWER_OPTIMIZATION

System capability: SystemCapability.PowerManager.PowerManager.Core

Parameters

Name Type Mandatory Description
mode DevicePowerMode Yes Power mode.

Return value

Type Description
Promise<void> Promise that returns no value.

Error codes

For details about the error codes, see Power Manager Error Codes.

ID Error Message
4900101 Operation failed. Cannot connect to service.

Example

power.setPowerMode(power.DevicePowerMode.MODE_PERFORMANCE)
.then(() => {
    console.info('set power mode to MODE_PERFORMANCE');
})
.catch(err => {
    console.error('set power mode failed, err: ' + err);
});

power.rebootDevice(deprecated)

rebootDevice(reason: string): void

NOTE
This API is supported since API version 7 and is deprecated since API version 9. You are advised to use power.reboot. The substitute API is available only for system applications.

Reboots the system.

Required permission: ohos.permission.REBOOT

System capability: SystemCapability.PowerManager.PowerManager.Core

Parameters

Name Type Mandatory Description
reason string Yes Reason for system reboot.

Example

power.rebootDevice('reboot_test');

power.isScreenOn(deprecated)

isScreenOn(callback: AsyncCallback<boolean>): void

NOTE
This API is deprecated since API version 9. You are advised to use power.isActive.

Checks the screen status of the current device. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.PowerManager.PowerManager.Core

Parameters

Name Type Mandatory Description
callback AsyncCallback<boolean> Yes Callback used to return the result. If the operation is successful, err is undefined and data is the screen status obtained, where the value true indicates on and the value false indicates off. Otherwise, err is an error object.

Example

power.isScreenOn((err, data) => {
    if (typeof err === 'undefined') {
        console.info('screen on status is ' + data);
    } else {
        console.error('check screen status failed, err: ' + err);
    }
})

power.isScreenOn(deprecated)

isScreenOn(): Promise<boolean>

NOTE
This API is deprecated since API version 9. You are advised to use power.isActive.

Checks the screen status of the current device. This API uses a promise to return the result.

System capability: SystemCapability.PowerManager.PowerManager.Core

Return value

Type Description
Promise<boolean> Promise used to return the result. The value true indicates that the screen is on, and the value false indicates the opposite.

Example

power.isScreenOn()
.then(data => {
    console.info('screen on status is ' + data);
})
.catch(err => {
    console.error('check screen status failed, err: ' + err);
})

DevicePowerMode9+

Enumerates power modes.

System capability: SystemCapability.PowerManager.PowerManager.Core

Name Value Description
MODE_NORMAL 600 Standard mode. It is the default value.
MODE_POWER_SAVE 601 Power saving mode.
MODE_PERFORMANCE 602 Performance mode.
MODE_EXTREME_POWER_SAVE 603 Ultra power saving mode.